Cypher 查询以查找具有 3 个关系的节点 [英] Cypher query to find nodes that have 3 relationships

问题描述

当我在寻找 2 个关系时，我想出了如何编写此查询，但不确定如何向查询添加更多关系.

I figured out how to write this query when I am looking for 2 relationships, but not sure how to add more relationships to the query.

假设您有一个以reader"和book"为节点的读书俱乐部数据库.'book' 节点有一个 'genre' 属性(用于定义这本书是小说、非小说、传记、参考文献等)在读者"节点和书"节点之间存在关系HasRead"，其中有人读过一本书.

Assume you have a book club database with 'reader' and 'book' as nodes. The 'book' nodes have a 'genre' attribute (to define that the book is a Fiction, Non-Fiction, Biography, Reference, etc.) There is a Relationship "HasRead" between 'reader' nodes and 'book' nodes where someone has read a particular book.

如果我想找到同时阅读小说和非小说书籍的读者，我可以执行这个 Cypher 查询:

If I want to find readers that have read both Fiction AND Non-Fiction books, I could execute this Cypher query:

Start b1=node:MyBookIndex('Genre:Fiction'), 
      b2=node:MyBookIndex('Genre:Non-Fiction')
Match b1-[:HadRead]-r-[:HasRead]-b2
Return r.ReaderName

上述查询的关键是 Match 子句，该子句将两个书籍别名输入到读者"节点的 r 别名中.

The key to the above query is the Match clause that has the two book aliases feeding into the r alias for the 'reader' nodes.

问题:我将如何编写查询以查找已阅读小说AND 非小说AND 参考书的用户?当您要查找的内容超过 2 件时，我一直在思考如何编写 Match 子句.

Question: How would I write the query to find users that have read Fiction AND Non-Fiction AND Reference books? I'm stuck with how you would write the Match clause when you have more than 2 things you are looking for.

推荐答案

您可以在单个 MATCH 子句中指定多行，用逗号分隔.例如，以下两个 MATCH 子句在语义上是等效的(并且将由引擎进行相同的评估):

You can have multiple line specified in a single MATCH clause, separated by commas. For example, the following two MATCH clauses are semantically equivalent (and will be evaluated identically by the engine):

//these mean the same thing!
match a--b--c
match a--b, b--c

您可以拥有任意数量的这些匹配项.因此，将其插入您的查询中，您会得到:

You can have any number of these matches. So, plugging that into your query, you get this:

start b1=node:MyBookIndex('Genre:Fiction'), 
      b2=node:MyBookIndex('Genre:Non-Fiction'),
      b3=node:MyBookIndex('Genre:Reference')
match b1-[:HasRead]-r,
      b2-[:HasRead]-r,
      b3-[:HasRead]-r
return r.ReaderName

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